Infrared radiation element and gas sensor using it

Abstract

In the infrared radiation element (A), a heat insulating layer 2, which has sufficiently smaller thermal conductivity than a semiconductor substrate 1, is formed on a surface in the thickness direction of the semiconductor substrate 1, and a heating layer 3, which is in the form of a lamina (plane) and has larger thermal conductivity and larger electrical conductivity than the heat insulating layer 2, is formed on the heat insulating layer 2, and a pair of pads 4 for energization are formed on the heating layer 3. The semiconductor substrate 1 is made of a silicon substrate. The heat insulating layer 2 and the heating layer 3 are formed by porous silicon layers having different porosities from each other, and the heating layer 3 has smaller porosity than the heat insulating layer 2. By using the infrared radiation element (A) as an infrared radiation source of a gas sensor, it becomes possible to extend a life of the infrared radiation source.

Description

TECHNICAL FIELD [0001] The present invention relates to an infrared radiation element and a gas sensor using it. BACKGROUND ART [0002] Various kinds of analyzers that use an infrared radiation source, such as an infrared gas analyzer, have been provided. A typical infrared radiation source used in such an analyzer is a halogen lamp. However, the halogen lamp is large and has a relatively short life span, so it is difficult to apply it to a small gas sensor that detects gas using infrared rays. [0003] So, as an infrared radiation source that can be miniaturized, an infrared radiation element formed by using a micro machining technology has been developed in many places (For example, see Japanese Non-examined Patent Publication No. 9-153640 (paragraphs [0027]-[0028], FIG. 2), Japanese Non-examined Patent Publication No. 2000-236110 (paragraphs [0017]-[0019], FIGS. 1 and 2), and Japanese Non-examined Patent Publication No. 10-294165 (paragraphs [0014]-[0015], FIG. 1)). [0004] In the ab...

AI Technical Summary

Benefits of technology

[0006] In view of the above problem, the object of the present invention is to provide an infrared radiation element that can have a long life, as compared with a conventional one, and a gas sensor using the infrared radiation element.

[0008] Therefore, because, in this infrared radiation element, the heating layer, which emits the infrared rays when being energized, is formed into a planar shape and is supported on the porous heat insulating layer, it is possible to increase the amount of radiation of the infrared rays, and it is possible to extend the life of the infrared radiation element.

Problems solved by technology

However, in the above infrared radiation element having the micro-bridge structure, the heat generator is subject to breakage, and it may be melted by the heat because the heat generator is in the form of a line, and only both ends of the heat generator are supported by the supporting substrate.

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